In exposure apparatuses used for manufacturing devices such as a semiconductor device and the like, a light emitted from a light source forms a secondary light source (a predetermined light intensity distribution on an illumination pupil in general) serving as a substantial surface light source consisting of multiple light sources, via a fly-eye lens serving as an optical integrator. Hereinafter, light intensity distribution on the illumination pupil will be referred to as “pupil luminance distribution”. The illumination pupil is defined as a position where by a function of an optical system between an illumination pupil and an irradiation target surface (a mask or a wafer in the case of the exposure apparatus), the irradiation target surface becomes a Fourier transform plane of the illumination pupil.
The light from the secondary light source, after being condensed by a condenser optical system, illuminates in a superimposed manner a mask on which a predetermined pattern is formed. The light having passed through the mask forms an image on the wafer via a projection optical system, and a mask pattern is projected and exposed (transferred) on the wafer. The pattern formed on the mask is fine, and in order to accurately transfer this fine pattern on the wafer a uniform illuminance distribution must be obtained on the wafer.
Conventionally, an illumination optical system is known that realizes a desired pupil luminance distribution using a movable multi-mirror which is configured of multiple minute mirror elements arranged in an array form and whose angle of inclination and inclination direction are driven and controlled individually. In this illumination optical system, because the movable multi-mirror used serves as a spatial light modulator, degrees of freedom is high regarding an outer shape and a distribution change of the pupil luminance distribution, which allows a pupil luminance distribution that is decided appropriately according to characteristics of the pattern that should be transferred having a complex outer shape and distribution to be achieved with good precision.
It is difficult, however, to achieve a desired imaging performance corresponding to a designed pupil luminance distribution, because the pupil luminance distribution which is actually formed on the illumination pupil turn outs to be slightly different from a designed pupil luminance distribution due to various causes, or optical properties other than the pupil luminance distribution turn out to be different from the conditions when the pupil luminance distribution was designed. Therefore, a method of performing optimization on the pupil luminance distribution is proposed (refer to PTL 1), so as to bring an imaging performance according to the actual pupil luminance distribution closer to a desired imaging performance according to the designed pupil luminance distribution.